Cyclonic separators rely on rotational effects to separate solids entrained in a fluid flow without using a filter. Cyclone separators are commonly used to separate dust and debris from the suction airflow of vacuum cleaners. Known cyclonic separators comprise a cylindrical or conical cyclone chamber with an air inlet and an air outlet. The air inlet is angled obliquely to the central axis of the cyclone chamber so that when debris laden air enters the cyclone chamber via the inlet, a rapidly rotating flowing air flow or vortex is established within the cyclone chamber. The air enters the cyclone chamber via an inlet and flows towards the opposite end. Centrifugal force generated by the circular air flow throws the dust particles towards the wall of the cyclone chamber from where they fall into a collection chamber. The air flows in an opposite direction through the center of the cyclone and is exhausted through an outlet. A vortex finder is located over the outlet through which the air flows. The function of the vortex finder is to ensure a stable rotational flow to improve separation performance. In particular, a vortex finder prevents turbulence in the vicinity of the outlet causing excessive noise, loss of pressure, and reduction of the collection efficiency of the separator. A vortex finder also prevents certain types of debris that does not readily fall into the collection chamber and that tends to remain in the inner air flow, from exiting the cyclone chamber through the outlet.
WO20064321A1 discloses a cyclonic separator having a vortex finder that seeks to reduce turbulence and loss of pressure in the vicinity of the cyclone outlet.
U.S. Pat. No. 4,260,401 discloses a cyclone-type particulate collector and concentrator wherein the outlet tube is provided with a conical concentrator having its sidewalls formed of a plurality of tapered, spaced, nested, generally U-shaped and cross-section vaned members between which the gas entering the outlet tube must pass in flowing to the outlet end of the outlet tube. A portion of the sidewall of the outlet tube of the cyclone-type particulate collector is provided with a gate to act as a particulate skimmer which opens into the gas inlet volute for recirculation of the skimmed particles.